OrchardCMS/OrchardCore · error · ArgumentException

Missing value in regexp query

Error message

Missing value in regexp query

What it means

RegexpQueryProvider.CreateQuery builds a Lucene RegexpQuery from a JSON object node. The 'value' property containing the regular expression is mandatory; if the object lacks it, the provider throws ArgumentException. The regexp pattern is what defines the term match, so it cannot be defaulted.

Solutions

  1. Add the required "value" string property with the regular expression, e.g. {"Title": {"type": "regexp", "value": "Orch.*"}}.
  2. Rename any 'pattern'/'regex' keys to exactly "value".
  3. Validate the query JSON shape before submitting it to the Lucene query provider.

Example fix

// before
{"Title": {"type": "regexp", "pattern": "Orch.*"}}
// after
{"Title": {"type": "regexp", "value": "Orch.*"}}
Defensive patterns

Strategy: validation

Validate before calling

if (node is JsonObject o && o.TryGetPropertyValue("value", out var v) && v.GetValueKind() == JsonValueKind.String && !string.IsNullOrEmpty(v.GetValue<string>())) { /* safe to call */ }

Type guard

static bool HasRegexpValue(JsonNode node) => node is JsonObject o && o.TryGetPropertyValue("value", out var v) && v.GetValueKind() == JsonValueKind.String;

Try / catch

try { var q = provider.CreateQuery(node); } catch (ArgumentException ex) when (ex.Message == "Missing value in regexp query") { // report 'regexp value required' to the user }

Prevention

When it happens

Trigger: A query node like {"field": {"type": "regexp"}} or {"field": {"type": "regexp", "boost": 2}} — type is regexp but the "value" property with the pattern is absent.

Common situations: Hand-written query JSON omitting the pattern; recipes migrated from other search providers using a different property name (e.g. 'pattern' or 'regex'); typos in the property name.

Understand the failure class

Background: "missing required argument" and "the following required arguments were not provided": what required-argument errors mean and how to fix them — this error's family across 20 libraries.

Related errors

AI-assisted analysis of OrchardCMS/OrchardCore@4306c0717f (2026-09-13). Data as JSON: /api/errors/1a4f0aebe5cb4e1d. Report an issue: GitHub.

Appendix: source

Thrown at src/OrchardCore/OrchardCore.Lucene.Core/QueryProviders/RegexpQueryProvider.cs:29

    {
        if (type != "regexp")
        {
            return null;
        }

        var first = query.First();

        switch (first.Value.GetValueKind())
        {
            case JsonValueKind.String:
                return new RegexpQuery(new Term(first.Key, first.Value.ToString()));

            case JsonValueKind.Object:
                var obj = first.Value.AsObject();

                if (!obj.TryGetPropertyValue("value", out var value))
                {
                    throw new ArgumentException("Missing value in regexp query");
                }

                // TODO: Support flags

                var regexpQuery = new RegexpQuery(new Term(first.Key, value.Value<string>()));

                if (obj.TryGetPropertyValue("boost", out var boost))
                {
                    regexpQuery.Boost = boost.Value<float>();
                }

                return regexpQuery;
            default: throw new ArgumentException("Invalid regexp query");
        }
    }
}

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